296 BATRACHIA CAUDATA. 
T'welve costal grooves. Brown or blackish, uniform, or with more or less numerous 
yellow spots of variable size and shape. 
Total length 200 millim., of which the tail takes about one-half. 
Axolotl. 
Azoloti, Cuv. in Humboldt’s Obs. Zool. tabb. 12, 14; Home, Philos. Trans. xxi. p. 419, tabb. 21-28 ; 
Bouleng. Batr. Grad. p. 44. 
Gyrinus mexicanus, Shaw, Nat. Misc. 1800, p. 343. 
Siren pisciformis, Shaw, Zool. iii. p. 612, t. 140. fig. 12. 
Siredon axolotl, Wag]. Ic. Amphib. t. 20. 
Azolotes guttatus, Owen, Ann. & Mag. N. H. 1844, xiv. p. 28. 
Axolotes maculatus, Owen, 1. c. 
Siredon mexicanus, Baird, Journ. Ac. N. Se. Philad. i. p. 292 (1849). 
Ambiystoma mexicanum, Cope, Proc. Ac. N. Sc. Philad. 1867, p. 184; Bull. U.S. Nat. Mus. no. 82, 
| p. 7 (1887); Brocchi, Miss. Sc. Mex., Batr. p. 104, t. 17. fig. 2, t. 17 bis. figg. 4, 5. 
Siredon humboldtii, Dum. et Bibr. Erpét. Gén. vii. p. 177. 
Siredon harlanii, Dam. et Bibr. |. c. p. 181, t. 95. 
Siredon dumerilit, Dugés, Ann. Sc. Nat. xv. p. 2, t. 10; La Nat. Mex. i. p. 241, t. 5 (1870). 
Siredon tigrina, Velasco, La Nat. Mex. iv. pp. 209-233, tabb. 7-9. 
On metamorphosis, cfr. A. Dum. Compt. Rend. 1865, lx. p. 763, Ixi. p. 775; Arch. Mus. ii. 
p. 265; Marsh, Am. Journ. xlvi. p. 864; Tegetmeier, P. Z. 8. 1870, p. 160; Weismann, Zeitschr. 
wiss. Zool. xxv. p. 297; Chauvin, ibid. xxvii. p. 522; Joly, Rev. Sc. Nat. Montpell. 1872, p. 7; 
Vaill. Bull. Soc. Philom. 1876; Osborn, Amer. Nat. 1900, p. 551. 
In the large series of Mexican Axolotls which are available for my examination, 
three forms may be distinguished, which, however, differ only in coloration :— 
1. The entire body covered with small, round, black spots. Albinos are not rare 
among wild specimens as well as among those bred in captivity. They attain a length 
of 260 millim., of which the tail measures one-half. To this form belong the Axolotls 
found in the vicinity of the city of Mexico (Doorman), in Lake Chalco (&. James), in 
Lake Texcoco (F. D. G.); also the majority of examples reared in England may be 
referred to this form. 
2. The sides of the body ornamented with irregular yellow spots, sometimes 
confluent and assuming the shape of a band; the upper parts generally uniformly 
blackish or with round black spots. These Axolotls are, on the whole, sometimes 
smaller than the preceding; I have seen them from the Colonia Briguela and La 
Cumbre de los Arrastrados, elevation 8500 feet, in Jalisco, and from La Laguna, 
Juanacatlan, elevation 6500 feet (Buller). 
3. Upper parts marbled with brown and yellow, both colours being distributed j in 
about equal proportions. Of this form I have seen only one specimen, which is the 
type of Owen’s A. maculatus; it came from the Sierra Madre, Chihuahua, and does 
not differ structurally or in its general form from the other Axolotls. 
